Tag Archives: Blood Vessel

Dr. C's Journal, Medicine, Men's Health

BLOOD VESSELS: HUMAN “PULMONARY CIRCULATION”

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Humans have a high energy requirement. Like a sports car we need to be turbosupercharged. We need an entirely separate Pulmonary circulation to handle our great oxygen demand.

Fish can get by on a single heart and circulation. They are “cold-blooded” and have no elevation of temperature above that in the environment. The water buoys them up, and they don’t need to constantly fight gravity.

Birds, and by extension, therapod dinosaurs, need more efficiency, and have a separate pulmonary circulation, just like we do. They share with us a DOUBLE CIRCULATION, a 4-chambered heart, with 2 entirely separate circuits.

In my residency, I saw a lot of congenital heart disease. In the process of development, the very early human embryo has a single circulation, just like “early” vertebrates, like fish.

In the process of development, the Systemic and Pulmonary circulations divide the previously unitary system into 2 separate systems, by a continuous spiral of partitions, or “septae”.

Ontogeny recapitulates Phylogeny: Development recaps Evolution. If this process of separation fails to happen in a given child, Congenital Heart Disease is the result:

  • IASD. Interatrial Septal Defect is failure to separate the Atria, the upper chambers of the heart;
  • IVSD, Interventricular Septal Defect, is failure to separate the Ventricles, the lower chambers of the heart;
  • AV Communis is both of the above, plus failure of Atria and Ventricles, the upper and lower chambers, to separate, giving one big inefficient chamber.

When you listen to the hearts of these children, there are prominent murmurs, or noises, which betray the presence of turbulence and inefficiency, the very thing that evolution “tried” to prevent.

In the normal Human Heart, the blood returns from it’s systemic circuit through the capillaries, depleted of oxygen, into the vena cava. It passes to the Right Atrium, through the tricuspid valves, to the right ventricle.

With the contraction of the heart, the blood goes through the pulmonary artery, into the pulmonary capillaries, into close contact with air-containing alveoli. The oxygen passes through the alveolar membrane into the capillary blood, which becomes red. The oxygenated blood then passes into the pulmonary veins and on into the left atrium, and the systemic circulation.

It is interesting, and essential that the systemic arteries contain red, oxygenated blood, and the Pulmonary artery contains blue, oxygen-depleted blood. The “tired” blood, returning from the body must be “pepped up” by passing through the pulmonary circuit, picking up oxygen in the process.

Similarly a clot, originating in a quiet vein, perhaps a dilated, or varicose vein, is pumped into the Pulmonary circuit, where it lodges in the tiny capillaries and produces a PULMONARY EMBOLISM.

The embolus clogs the pulmonary circuit, increasing resistance, raises the normally-low pulmonary artery pressure and produces PULMONARY HYPERTENSION, placing more load and strain on the Right Ventricle.

Pulmonary Hypertension is also caused by a variety of Lung, heart, inherited and kidney diseases, as well as by certain drugs, high altitude, and Obstructive Sleep Apnea.

Please check the Mayo Clinic discussion that follows.

–Dr. C

Pulmonary Hypertension Article

Medicine, Men's Health, Rx, Women's Health

DR. C’S MEDICINE CABINET: “WHY PATIENTS TAKE ELIQUIS”

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Eliquis nicely illustrates my contention in the Overview of Metabolism, that the body is a vast collection of pathways, or “supply chains”. Eliquis blocks a critical enzyme in the pathway leading to coagulation, or clotting” as the product.

Why in the world you want to block clotting? The staunching of blood flow, clotting, has saved countless hordes of early, Paleolithic humans, and continued useful through the bloody Roman and Medieval times, right through the violent 20th Century.

Recently, however, wars are becoming somewhat less popular, and eating excessively more popular, leading to a strange situation. Our evolutionarily-preserved CLOTTING mechanism is now leading to MORE problems than it is solving.

Obesity and type 2 Diabetes are leading to the production of so much fat, that it has to be stored in our arterial walls, clogging the blood flow to our Hearts and Brain, among other areas. This, and the somewhat surprising trend towards longer lives has led to an increase in a variety of age-related illnesses.

When I reached 80 years of age I developed Atrial Fibrillation, a condition leading to a tendency to form clots in my quivering atria, the upper chambers of my heart. To decrease the likelihood of clots getting into my blood stream, lodging in my brain and causing STROKE, my cardiologist started me on Eliquis, an anti-coagulant/blood thinner.

Drugs have three names. The proprietary name, Eliquis in this case, is given by the patenting company to be memorable; q,z,and x are popular letters. The second is the FDA drug name, Apixaban. The drug name often gives the doctor a clue as to its type: xaban refers to inhibiting (banning) of factor 10a (Xa). The third name is a chemical name of interest to biochemists and drug researchers.

When I started the Eliquis, at first unknown to me, I started to bleed internally, leading to a drop in my hemoglobin down to 8.6. I will go into this story when I start going through “how to read your laboratory report”.

I found that reducing my Eliquis from 5mg. to 3.75 mg. allowed me stabilize my hemoglobin by taking extra iron, which I will discuss later.

The doseage selected when the drug company markets a drug is fairly arbitrary, and usually involves round numbers. Interestingly, there is a 2.5mg. Eliquis, which is given if you meet 2 out of 3 criteria. I meet only one and am only 5 pounds shy of the second, in case you think (like my cardiologist does) that I’m taking a risk.

I believe that, whenever you are given a medication, you should be educated about the medicine, and the problem it is intended to benefit. Today’s physician often does not have the time to do this. The internet, including this website, offers a corrective.

I am trying my best to be helpful to you as a Patient Advocate. You and I both must have a doctor to rely upon. But to get the most out of our care, WE MUST BE INFORMED.

–Dr. C